Ningaloo eclipse: moon shadow speed and land surface temperature effects from Himawari-9 satellite measurements

Abstract

A total solar eclipse occurred on April 20, 2023, with the umbral shadow touching the Australian continent over the Ningaloo coastal region, near the town of Exmouth, Western Australia. Eclipse totality lasted ∼1 min, reaching totality at ∼03:29 UTC and happened under cloudless skies. Here, we show that the speed of the Moon’s shadow over the land surface can be estimated from 10 min sampling in both the infrared and visible bands of the Himawari-9 geostationary satellite sensor. The cooling of the land surface due to the passage of the Moon’s shadow over the land is investigated, and temperature drops of 7 K to 15 K are found with cooling rates of 2±1.5 mK s−1. By tracking the time of maximum cooling, the speed of the Moon’s shadow was estimated from thermal data to be 2788±21 km h−1 and from the time of minimum reflectance in the visible data to be 2598±181 km h−1, with a notable time dependence. The methodology and analyses are new and the results compare favorably with NASA’s eclipse data computed using Besselian elements.